Capodastros, or capos as they are now commonly called, are devices that are placed about the necks of stringed instruments such as guitars, banjos, ukuleles, and the like to depress the stings of the instrument and thereby shorten the effective vibrating length of the strings and alter their pitch.
U.S. Pat. Nos. 390,612, 468,193, and 4,149,443 disclose capos similar to the invention capo. These patented capos each include (1) a frame or body that has a top arm or presser bar that is designed to extend transversely over the strings and an integral side arm that extends from the presser bar laterally of the instrument neck; (2) a clamping jaw that is pivotally connected to the side arm; and (3) a lever mechanism pivotally attached to the side arm below the clamping jaw that engages the jaw and thereby causes the jaw to be closed against the back of the neck thus forcing the fingerboard up against the top arm to depress the strings that run longitudinally along the fingerboard. In U.S. Pat. No. 390,612 the lever mechanism is a cam lever that when pivoted bears against the bottom of the clamping jaw. In U.S. Pat. No. 468,193 the lever mechanism is a lever-V-spring assembly wherein one end of the spring is attached to the lever and the other is attached to the jaw. When the lever is pivoted the spring is compressed and the jaw is forced against the back of the neck. U.S. Pat. No. 4,149,443 discloses a variation of the capo of U.S. Pat. No. 390,612 in which the bearing surface of the cam lever has dwell and rise surfaces. When the cam lever is pivoted the jaw is cammed incrementally toward the back of the instrument neck. The pressure exerted by these cam lever type capos depends upon the degree to which the cam lever is rotated. To obtain the same pressure each time the capo is applied to the neck, the cam must be rotated to exactly the same position. While the lever-V-spring type capo applies the same pressure each time it is applied, the capo is not readily adjustable for use on other instruments.
The principal object of the invention capo is to provide a capo that is adjustable, is fast and easy to use, exerts the same pressure each time it is used, has a positive locking action when applied to the instrument neck, and may be released instantly.